Vibrating apparatus for handling loose material



Nov. 18, 1958 L. w. JOHNSON VIBRATING APPARATUS FOR HANDLING LOOSEMATERIAL 2 Sheets-Sheet 1 Filed April 25, 1956 INVENTQR. LOUIS W.JOHNSON A T TOIPNE Y5 Nov. 18, 1958 L. w. JOHNSON I VIBRATING APPARATUSFOR HANDLING LOOSE MATERIAL Filed Anril 25, 1956 2 Sheds-Sheet 2 mm T mmmm J w s m 0 LY B O G 5 .l W F w \s EW v\ W K 2m A TTORNEYS UnitedStates Patent VIBRATING APPARATUS FOR HANDLING LOOSE MATERIAL Louis W.Johnson, Eugene, Oreg.

Application April 23, 1956, Serial No. 579,836

8 Claims. (Cl. 209-3665) This invention relates to vibrating apparatusfor handling loose articles andparticularly to screening apparatusespecially adapted for use in screening crushed rock and the like.

Prior screening apparatus for use with crushed rock have beenessentially of two types, the two bearing type and the four bearingtype. The two bearing type includes a screening box which is resilientlymounted or suspended, usually on a base frame, and further includes atransverse shaft which is journaled on the box in two spaced bearingsand carries at each end an eccentric weight. The shaft is rotated tocause the screening box to vibrate. The four bearing apparatusisessentially similar, except that the shaft is also journaled in anadditional set of bearings on the base frame, the two sets of bearingsbeing eccentric to each other.

Both types of apparatus have operational disadvantages, including thefact that the weights, being of constant mass, cannot compensate forvariations in the effective mass of the box, which is caused bydifferent loadings of the box and also other factors, such as theadherence of sticky material to the screens. Thus, load variations causevariations in the amplitude of vibration of a box, resulting ininadequate screening.

In four bearing screening apparatus, the weights are arranged incounterbalancing relation with respect to the box, so that under idealconditions there is little vibration of the base frame. However, idealconditions rarely exist because of the different loadings of the box andother factors, and hence there is considerable tendency for the'fourbearing apparatus operating under ordinary conditions to vibrate thebase frame and thus result in severe wear on the bearings connecting thebox to the base frame.

With two bearing screening apparatus, the box is not mounted on theframe by bearings and hence no restraints are placed on vibratingmovement of the box.

Thus the box is subjected to objectionable violent shaking andvibrationduring starting and stopping. Also, the heavy weights hang downwardlywhen at rest and it requires excessive power to start the two bearingapparatus because of the necessity of lifting the weights up and overcenter without the counterbalancing aid of the box as is the case in thefour bearing apparatus. .This has required the use of larger motors fortwo bearing machines than for four bearing machines.

It is a main object of the present invention to pro vide a screeningapparatus having a vibration producing means so constructed that itautomatically adjusts to the mass of the screening box, within thelimits of the apparatus, thus to obtain uniform amplitude of vibrationdespite variations in the effective mass of the screening X box. t

It is a further object of the present invention to provide a screeningapparatus in which the vibrating producing means 'is in a balancedcondition 'when starting and stopping the machine so thatless vibrationis experienced I Patented Nov. 18, 1958 ice at such time and also lesshorespower is required to 0p erate the apparatus at such times.

. The apparatus of the present invention is characterized by including ascreening. box having a transverse shaft extending therethrough andjournaled thereon. On each end of the shaft a weight means is rotatablymounted about an axis offset or eccentric to that portion of the shafton which the box is journaled. Each weight means includes at least twoweights which are so freely journaled for rotary movement as to beoperable automatically to assume positions to obtain uniform amplitudeof vibration.

Various other objects of the present invention will be apparent from thefollowing description taken in con nection with accompanying drawingswherein:

Fig. l is a side View of a two bearing machine embodying the concepts ofthe present invention;

Fig. 2 is an end view looking in the direction of the arrows 2.2 in Fig.1;

Fig. 3 is an enlarged sectional view taken along line 3-3 of Fig. 2,showing more fully details of construction;

Fig. 4 is a plan view taken in the direction of the arrows 4.4 of Fig.3;

Fig. 5 is an enlarged sectional view of a weight means taken along line55 of Fig. 1;

Fig. 6 is a vertical sectional view taken along line 66 of Fig. 5,showing the weights in their rest positions;

Fig. 7 is a view similar to Fig. 6 but showing the weights in operativepositions;

Fig. 8 is a schematic view illustrating the mode of operation of aweight;

Fig. 9 is a side view of a four bearing machine;

Fig. 10 is an enlarged sectional view taken along line 1010 of Fig. 9,showing the construction of a weight means, and

Fig. 11 is a sectional view taken along line 1111 of Fig. 10. I

Referring to the accompanying drawings, Figs, 1 through 6 show a twobearing machine embodying the concepts of the present invention. Themachine includes an open rectangular base frame 11 on which a screeningbox 13 is resiliently mounted. The right-hand end of the box, as theparts are disclosed in Fig. l, is its loading end and its left-hand endis its delivery end.

The manner of supporting the box is as follows. There are four similarmounts, each including a coiled com pressing spring 15 (Fig; 3) seatedon a base member 17 and bearing against a head block clamp 19, in whichthe free ends of a cable 21 are secured. The lower por tion of the cableextends around and is secured. to a stub shaft 23 which is in turnsecured to the side of the screening box 13. Each delivery end mount hasthe base mem-: ber 17 thereof fixed to the frame 11, whereas the basemember of eachloading end mount is fixed. on a pillar 29 secured to theframe 11. Thus the loading endof the box is disposed at a higherelevation than the delivery end of the box. i

The screening box 13 is provided with one or more appropriate screens orcourses 31, Fig. 1, which extends longitudinally of the box and fromside to side thereof. Three screens are shown, the upper screen beingthe coarsest, theintermediate screen being somewhatfiner, and the lowerscreen being the finest. The bottom of the screeningbox is open so thatmaterial passing throughthe bottom screen drops into a pile or on asuitable conveyor beneath the box. Suitable conveyors may also beprovided at the delivery end of the box to receive loose material whichhas been graded.

The screening box is equipped with a transverse shaft housing 33, Fig.5, which is fixed to the sides of the box. Extending through the housingis a shaft 35, each end of which has a first reduced portion 37 and asecond reduced portion 39. The shaft is mounted in the housing 33 bybearings 36 which fit on reduced portions 37, suitable bearing retainers43 and seals 45 being provided for the bearings. Portions 39 areeccentrically disposed relative to portions 37 but concentricallydisposed relative to the central portion of the shaft and also theextreme end portions of the shaft. The shaft is driven by means of amotor .47 which is mounted on the frame 11 and connected to the shaft bya flexible belt drive 49 which includes a pulley 50 fixed to an end ofthe shaft.

Fixed concentrically on each of the shaft portion-s 39 is aweight meansincluding a hollow disc shaped casing51 which has a hub 53 keyed at 55to the shaft portion 39.. A nut 56 retains each casing on the shaft 35.

,Within each casing 51 is a pair of fan shaped weights 57 and 59, Fig.6, which are of equal mass and are rotatably mounted by means ofbearings 61 on the hub 53 of the casing. Each casing is provided with apair of stops 71 and 73 for its weight 57, and 75 and 77 for its weight59. Thus each weight may revolve freely an arcuate distance between thelimits of the associated stops, but the stops maintain the weightgenerally in opposed relation and on opposite sides of a line throughthe taxes of shaft portions 39 and 37 Pivotally mounted on the weight 59of each casing is a pawl 81 which is adapted to engage ratchet teeth 83formed on the hub portion of the associated weight 57. A biasing means,such as a preloaded spring 85, is mounted on the weight 59 and urges thepawl into engagement with the ratchet teeth. The biasing means are soconstructed that before the machine is up to rated speed, centrifugalforce Will cause the pawl to disengage from the ratchet teeth and thusprovide for rotary movement of the weights relative to the casing. Thecasing may be filled or partially filled with a quantity of oil whichserves as a lubricant and dampens movement of the weights relative tothe casing.

The operation of the machine is as follows. Initially, the weights 57and 59 are locked in positions approximately 180 degrees from each otheragainst the stops 71 and 75 by the pawl 81, Fig. 6. In fact, the weightsare arranged with their upper edges slightly closer together than theirlower edges so that the center of gravity of said weights and easingcoincides with the axis of shaft portions 37. This provides for absolutebalance of the machine when starting. Thus the box 13 will remainstationary while the weight means are being rotated up to speed .and alow horsepower motor can turn over the weight means since they are in abalanced condition.

Just before the box gets up to rated speed, the pawls 81 are forcedoutwardly under the influence of centrifugal force to release theweights 57 and 59 which automatically leave the stops 71 and 75 andswing to positions similar to those in Fig. 7 to cause vibration of thebox about the axis of shaft portions 39 as a center, for reasonspresently to be explained. If the mass of the screens of the screeningbox increases because of the adherence of clay and the like, or forother reasons, the weights will move further toward one another tomaintain a uniform amplitude of vibration. I

While the machine is being stopped, the weights will return to theirFig. 6 positions because the pawl will move back intoengagement withteeth 83 and allow relative movement of the weights, under the influenceof gravity, onlyin a direction separating the weights from one another.

The theory of operation of the weights is as follows. Referring to Fig.8, if weights A are mounted for rotation about an axis 'B and axis B isrotated in an orbit about axis C, the weights under the influence ofcentrifugal force will tend to move to positions where their centers ofgnavity are aligned with the axes B and C, as shown in dotted .lines. Ifthe axis C is located on a floating or resiliently mounted box, movementof the weights A from their rest positions toward the dotted lineposition will be accompanied by increased vibration of the box in anorbital movement and cause a shift in the center of motion from axis Cto axis B as a center, at which time the mass of the weights multipliedby the distance between the centers of gravity of the weights and axis Bequals the effective mass of the box multiplied by the distance betweenaxes B and C. Under these conditions, there is no longer any centrifugalforce urging continued movement of the Weights A toward their alignedpositions, so that such movement ceases and leaves the weights atintermittent positions, for instance the dot-dash positions shown. Infact, centrifugal force-will maintain the weights at such intermittentpositions.

It the effective mass of the box should increase, such as might becaused by the adherence of clay to the screens thereof, or for any otherreason, the center of motion will shift slightly from axis B and thusthe axis B will move through a small orbit. Thus centrifugal force willcause further movement of the weights A toward their aligned positions,thus automatically to compensate for the change in the effective mass ofthe box and thus maintain a uniform amplitude of vibration of the box.

The weights 57 and 59 of the machine of Figs. 1 through 7 operate in theabove described manner with axis By being the axis of shaft portions 39and axis C being the axis of shaft portions 37. A requirement forobtaining the desired results is that the weights be heavy enough tocause the box to vibrate about the axis of shaft portions 37 at a timewhen the weights are disposed at intermediate positions between theirinactive rest positions and their aligned conditions. If the weights didnot meet this requirement, they would assume aligned positions duringoperation of the machine without causing the center of motion to move tothe axis of shaft portions 39, and thus the weights could not counteractdecreasingamplitude of vibration which would be caused by an increase inthe effective mass of the box.

It is pointed out that since there is a pair of weights at each side ofthe machine, the machine will vibrate at a uniform amplitude even thoughone side of the machine is heavier than the other.

Fig. 9 shows a modified form of the invention incorporated in a fourbearing type screening apparatus. This appanatus includes a base frame91 and a screening box 93 similar to screening box 13. In thisconstruction, the screening box is resiliently mounted on the base frame91 in part by resilient mounts 95 in the same manner as box 13 ismounted by mounts 15 on frame 11, or in equivalent fashion to permitvibrating movement of the box. The box is also mounted on the frame 91by means of a transverse shaft 97, having at each end a reduced shaftportion 98 mounted by a bearing 101, a housing 102, a rubber bushing 103and a pillow block 104 on the frame 91. The central portion of the shaftis journaled on box 93 by .a pair of bearings 105, one of which is shownin Fig. 10. The shaft is driven by a motor and belt drive unit 106.

A weight means is rotatably mounted on a shaft portion 107 adjacent eachend of the shaft and each of these weight means includes a pair offreely rotatable weights 111 and 113, Fig. 11, which are similar toweights 57 and 59 of the previously described form of the invention.Shaft portions 98 and 107 are concentric relative to one another buteccentric relative to the central portions of shaft 97. The weights areso located circumferentially of the shaft as to be disposed in positionsto counterbalance the vibrating effect of the box on the frame 91.

A lock 115 extends through guides 117 on the casing and engages teeth119 on the weights. The lock is spring loaded by springs 121 bearingagainst a base 123, the parts being constructed so that the lock willdisengage just before the machine gets up to rated speed under theinfluence of centrifugal force and to re-engage just after the machinespeed falls below rated speed. Thus, this maintains the weights atapproximately their running positions when the machineis starting orstopping so that the box does not vibrate the frame 91. However, theweights may adjust to variations in the effective mass of the box whenthe machine is operating at rated speed.

Although the concepts of the invention have been shown as having beenincorporated in a screening apparatus, they could also be incorporatedin apparatus for handling other loose articles or material. Among theimportant advantages obtained by the present invention is prolongedbearing life because of the balanced operating conditions of themachines.

Having described the invention in what is considered to be the preferredembodiment thereof, it is desired that it be understood that theinvention is not to be limited other than by the provisions of thefollowing claims.

I claim: r

1. A screen vibrating apparatus for imparting constant amplitude ofvibration to a screen member whose effective mass varies in accordancewith loading and other conditions, comprising means mounting said memberfor vibrating movement, a pair of weightsmounted on said member forswinging movement about a first axis and for rotary movement about asecond axis parallel to said first axis but offset therefrom so thatswinging movement of said weights about said first axis changes thedistance between the center of gravity of each weight and said secondaxis, means for rotating said weights about said second axis to causesaid weights to move about said first axis toward positions at whichsaid dis tance is a maximum, said weights having sufficient mass tocause said member to vibrate about said first axis before said weightsreach such positions so that upon an increase in the effective mass ofsaid member said weights will swing toward such positions to compensatefor such increase and will swing away from such positions to compensatefor a decrease in the effective mass of said member thus to maintainsaid member vibrating about said first axis to maintain a uniformamplitude of vibration.

2. A screen vibrating apparatus for imparting constant amplitude ofvibration to a screen member whose effective mass varies in accordancewith loading and other conditions, comprising means mounting said memberfor vibrating movement, weight means mounted on said member for turningmovement about a first axis and for rotary movement about a second axisparallel to said first axis but ofiset therefrom so that turningmovement of said weight means about said first axis changes the distancebetween the center of gravity of said weight means and said second axis,means for rotating said weight means about said second axis to causesaid weight means to move about said first axis toward a position atwhich said distance is a maximum, said weight means having sufiicientmass to cause said member to vibrate about said first axis before saidweight means reaches such position so that upon an increase in theeffective mass of said member said weight means will swing toward suchposition to compensate for such increase and will swing away from suchposition to compensate for a decrease in the effective mass of saidmember thus to maintain said member vibrating about said first axis tomaintain a uniform amplitude of vibration.

3. A screen vibrating apparatus for imparting constant amplitude ofvibration to a screen member whose effective mass varies in accordancewith loading and other conditions, comprising means mounting said memberfor vibrating movement, a pair of weights mounted on said member forswinging movement about a first axis and for rotary movement about asecond axis parallel to said first axis but offset therefrom so thatswinging movement of said weights about said first axis changes thedistance between the center of gravity of each weight and said secondaxis, means for rotating said weights about said second axis to causesaid weights to move about said first axis toward positions at whichsaid distanceflis a maximum, said weights having sufiicient mass tocause said member to vibrate about said first axis before said weightsreach such positions so that upon an increase in the effective mass ofsaid member said weights will swing toward such positions to compensatefor such increase and will swing away from such positions to compensatefor a decrease in the effective mass ofsaid member thus to maintain saidmember vibrating about said first axis to maintain a uniform amplitudeof vibration and means operable when said machine has ceased operatingat normal speeds for disposing said weights in places at which theircenters of gravity are generally on opposite sides of said first axis sothat said machine may start or stop without excessive vibration.

4. A screen vibrating apparatus for imparting constant amplitude ofvibration to a screen member whose effective mass varies in accordancewith loading and other conditions, comprising means mounting said memberfor vibrating movement, weight means mounted on said member for turningmovement about a first axis and for rotary movement about a second axisparallel to said first axis but offset therefrom so that turningmovement of said weight means about said first axis changes thedistancebetween the center of gravity of said weight means and saidsecond axis, means for rotating said weight means about said second axisto cause said weight means to move about said first axis toward aposition at which said distance is a maximum, said weight means havingsufficient mass to cause said member to vibrate about said first axisbefore said weight means reaches such position so that upon an increasein the eifective mass of said member said Weight means will swing towardsuch position to compensate for such increase and will swing away fromsuch position to compensate for a decrease in the effective mass of saidmember thus to maintain said member vibrating about said first axis tomaintain a uniform amplitude of vibration and means operable when saidmachine has ceased operating at normal speeds for disposing said weightmeans at a place at which its center of gravity is near said first axisso that said machine may start or stop without excessive vibration.

5. A vibrating apparatus for imparting constant amplitude of vibrationto a member whose effective mass varies in accordance with loading andother conditions, comprising means mounting said member for vibratingmovement, a pair of weights mounted on said member for swinging movementabout a first axis and for rotary movement about a second axis parallelto said first axis but offset therefrom so that swinging movement ofsaid weights about said first axis changes the distance between thecenter of gravity of each weight and said second axis, means forrotating said weights about said second axis to cause said weights tomove about said first axis toward positions at which said distance is amaximum, said weights having sufiicient mass to cause said member tovibrate about said first axis before said weights reach such positionsso that upon an increase in the effective mass of said member saidweights will swing toward such positions to compensate for such increaseand will swing away from such positions to compensate for a decrease inthe effective mass of said member thus to maintain said member vibratingabout said first axis to maintain a uniform amplitude of vibration.

6. A screen vibrating apparatus for imparting constant amplitude ofvibration to a screen member whose effective mass varies in accordancewith loading and other conditions, comprising means mounting said memberfor vibrating movement, a pair of weights mounted on said member forswinging movement about a first axis and for rotary movement about asecond axis parallel to said first axis but offset therefrom so thatswinging movement of said weights about said first axis changes thedistance between the center of gravity of each weight and said secondaxis, means for rotating said weights about said second axisto causesaid weights to move about said first axistoward ositions at which saiddistance is a rnaximum, said weights having sufficient mass to causesaid member to vibrate about said first axis before said weights reachsuch positions so that upon an increase in the effective mass of saidmember said weights will swing toward such positions to compensate forsuch increase and will swing away from such positions to compensate fora decrease in the effective mass o'fsaid member thus to maintain saidmember vibrating about said first axis to maintain a uniform amplitudeof vibration, said weights being freely movable within limits withoutrestraint so that the centrifugal force on said weights determines theirposi' tions during normal operation of said machine.

7, A screen vibratingrapparatus for imparting constant amplitude ofvibration to a screen member whose effective mass varies in accordancewith loading and other conditions, comprising means mounting said memberfor vibrating movement, a pair of weights mounted on each side of saidmember for swinging movement about-a first axis and for rotary movementabout a second axis parallel to said first axis but offset therefrom so.that swinging movement of said weights about said first axis changes thedistance between the center of gravity of each weight and said secondaxis, means for rotating said about said first axis to maintain auniformamplitude 0f vibration.

8. "A screen vibrating apparatus for imparting constant amplitude ofvibration to a screen member whose etfec tive mass varies in accordancewith loading andother conditions, comprising means mounting saidmember-for vibrating movement, a shaft journaled on sai'dumember andhaving an eccentric portion, a pair of weights mounted on said portionfor swinging movement about the axis thereof and for rotary movementabout the axis of said shaft so that movement of said weights about thefirst-mentioned axis changes the distance between the center of gravityof each weight and the second-mentioned axis, means for rotating saidweights about said secondmentioned axis to cause said weights to moveabout said first-mentioned axis toward positions at which said distanceis a maximum, said weights having sufficient mass to cause said memberto vibrate about said first-mentioned axis before said weights reachsuchyposition so that upon an'increase in the effective mass of saidmember said weights will swing toward such positions to compensate forsuch increase and will swing away from such positions to compensate fora decrease in the effective mass of saidimember thus to maintain saidmember vibrating about said first-mentioned axis to maintain a uniformamplitude of vibration.

References Citedin the file of this patent UNITED STATES PATENTS2,063,509 Lacy Dec. 8, 1936 2,144,382 Lincoln et al. Jan. 17, 19392,208,596 Parks July 23, 1940 2,528,620 Stroud Nov. 7, 1950 FOREIGNPATENTS 645,064 Great Britain Oct. 25, 1950 UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION Patent No, 2,860,783 November 18, 1958 LouisW. Johnson It is hereby certified that error appears in the printedspecification of the above numbered patent requiring correction and thatthe said Letters Patent should read as corrected below.

Column 2, line 3'7, for "a sectional" read no a vertical sectionalcolumn 8, line 19, for "position" read w positions m Signed and sealedthis 7th day of April 1959.,

(SEAL) Attest:

KARL H. AXLINE ROBERT C. WATSON Aime-ting OHLper Commissipner of Eatcnts

